that $600-odd was in $CAN
lol you're comparing a real steel pistol's price to an AS assault rifle's price? let's do some direct comparison.
Classic Army G36K: $311 US
HK G36K: goes used for $1100 - $1500 US.
Now an airsoft version of your SIG would cost in the area of $170 for a nice Tanaka version.
like Drake said, it's really a matter of personal preferance and deep pockets. and you live in the states, you can get whatever you want at asshat low prices. give airsoft a try lol, you can think of it as being as realistic as possible with zero flesh wounds!